Production of barium-chromium-copper-alumina containing catalyst



Patented Apr. 7, 1953 PRODUCTION .OFYBARIUM- CHROMIUM-COP- PER-ALUMINACONTAINING CATALYST Alexander F. .MacLe'an, Robstown, Tex assignor to'Celanese Corporation of America, :New :York,

No Drawing, Original application July 23, 1949,

Serial No. 106,502. Divided and this application July 25, 1950, SerialNo. 1275;875

LClaim. .(Cl. 252-465) This invention relates to the dehydrogenationof'alcoholseand :relates more particularly to the catalytic vaporphaseidehydrogenation oilalcohols to form 'aldehydes :and .ketones.

' This application :is a division of my application S. NO. .1'06;502,filed July '23, 19.49.

An object :of this invention is the provision of an improved catalystadapted to be employed in fluidized dorm in the "vapor phase catalyticdehydrogenation of alcohols to aldehydes and ketones and to a process"for the production of said novel; catalyst...

. Other'i-{objiects of this "invention will appear from theifollowing:detailed description.

The vapor phase catalytic dehydrogenation of alcohols isareactionwidely:employedindustrially for the production of many carbonylcompounds.

For example, the dehydrogenation of isopropyl alcohol is being employedindustrially for the production of acetone and n-propyl alcoholfor theproduction "of pr.opionaldehyde. "Similarly,

I ethanol may be readily dehydrogenated to acetaldehydeuwhich, onoxidation, is converted to acetic acid. The reaction is -a reversibleone and those catalysts which have a dehydrogenating efiect also serveas hydrogenation catalysts under certain conditions. .In addition, ithas also been foundathat many catalysts whichvmay be :em-

ployed tor dehydrogenation are not specific for said :rea'ction :onlyand also exhibit a tendency to act :as dehydration catalysts, whichgives rise to obniously undesirableside reactions. The dehydrogenationcatalysts employed heretofore have been utilized :in the torm of .avfixedhed. The use of .a fixed catalyst .bed, however, makes temperaturecontrol somewhat difficul-t .and frequently leads to excessivedecomposition and dehydration.

In addition, .a fixed bed catalyst cannot be regenerated concurrent withthe dehydrogenation cycle butmust beregeneratedin a separate cycle asoxygen or oxygen .in air mixed with the feed disappears rapidly at theinlet of the fixed bed k; and loses its efiect over most of the bed.

I have now .iound that the catalytic vapor phase dehydrogenation ofalcohols and ketones fluidized. catalytic. operation and the originalcatalyst particles retain their initial hi h catalytic :activity :overprolonged vperiods of operation. Furthermore, should the activity ofsaid catalyst fall below that degree which is essential for economicoperation, the catalyst may be readily regenerated and restored to theoriginal :high state of-activityby merely heating in :air so as toburniofi any carbon deposited thereon, which deposits are usuallyresponsible for any observed decrease .in activity. These carbon:deposits :are normally burned off :at least in part concurrent with thedehydrogenation when :oxygen or :air is presentin the vapors passingoverthe catalyst. Since the bedis in a turbulent state the partiallycarbonized catalysttin the entire bed-is generally exposed to gascontaining sufficient oxygen to burn oli the carbon concurrent with thedehydrogenation cycle.

The novel catalyst of my invention may be prepared by adding inactivealumina to an aqueous solution formed by dissolving barium hydroxide inwater, neutralizing the resulting solution with glacial acetic acid andadding copper nitrate and chromium nitrate thereto, the slurry which isobtained on addition of the inactive alumina being then evaporated todryness. The

coated particles thus obtained have no catalytic,

activity, however, without a suitable activation treatment. Theparticles may be activated .by heating them in air .at atemperature of600 to 7.00 Enter about 1 to 4 hours. The heating .or activation"treatment in the presence of air converts the metal-salts, deposited onthe alumina particles by the evaporation of water from the slurry formedin the manner described above.

into the corresponding oxides and in this form the catalyst particlesexhibit the desired activity.

Thus, informing my novelcatal-yst, from 5 to 15 parts by weight ofbarium hydroxide are dissolved in 100 parts by weight of hot distilledwater maintained at a temperature or .80 to 1.00" F. and the solutionobtained is then neutralized withglacial acetic acid. -About20 to 45parts by weight of copper nitrate arethen added to the neutralizedsolution together with .1 to 3 parts by weight of chromium nitrate. Thelatter .is preferalol-y added as-a 30 to 50% by weight aqueous solution.Inactive alumina particles of to 200. mesh size are then added in anamount of about35o parts by weight and the resultingslurry thus formedis thendried with stirring. Stirring is .employedso'as to avoid theformation of large lumps. Drying may be effected conveniently inasteamejacketed vessel, ior'example. The coated alumina particles thusobtained are then activated by being heated in air in fluidized form asdescribed above. Activation is most advantageously effected by heatingthe coated catalyst particles at a temperature of about 600 F. for about1 hour.

In order further to illustrate my invention, but without being limitedthereto, the following examples are given:

Example I A catalyst suitable for the dehydrogenation of alcohols isprepared in the following manner:

3.0 parts by weight of barium hydroxide octahydrate are dissolved inabout 23 parts by weight of distilled water at a temperature of 80 F.and the resulting solution neutralized, i. e. to a pH of 6, by theaddition of glacial acetic acid thereto. 13 parts by weight of coppernitrate: 3H2O are then added to the solution together with 0.5 part byweight of a 50% by weight aqueous solution of chromium nitrate: 9I-I;O.A slurry is then formed by the addition of 75 parts by weight ofinactive alumina, of between 100 to 325 mesh particle size, to theaqueous solution with stirring. The paste thus formed is then dried in asteam jacketed kettle while being stirred to avoid lumping. The driedparticles are then heated in a stream of air at 600 F. for 1 hour toconvert the metal salts present thereon to the oxides, the coatedalumina particles being thus activated for use in catalyticdehydrogenation reactions. The catalyst comprises finely-dividedparticles of inactive alumina having a mixture of 1.0 to 4.0% by Weightof barium oxide, 0.05 to 1.0% by weight of chromium oxide and 2 .to 6%by weight of cupric oxide on the surfaces thereof.

Example II 50 pounds per hour (0.77 pound mol) of isopropyl alcohol arevaporized, mixed with 28 pounds per hour of water (1.7 pounds mols) inthe form of steam and 590 cubic feet per hour of air at standardconditions (i. e. 60% of the oxygen, in the form of air, theoreticallynecessary to combine with the hydrogen splitting oif underdehydrogenation conditions when both conversion and efficiency are100%). The vapor mixture thus formed is continuously passed into areactor containing 100 pounds of the activated catalyst particlesprepared as described in Example I, the,

reactor being suitably heated so that the particles are maintained at atemperature of 675 F. The catalyst particles have a static depth of 3.5feet. The velocity of the vapors passing throu h the catalyst ismaintained sumciently high to effect a fluidization of the catalystparticles, said velocity being about 1 foot per second. The depth of thecatalyst bed is such that the vapors passing through the reactor whichcontains the catalyst particles are in contact with the fluidizedcatalyst particles for about 3.5 seconds. The mixture of gaseousreaction products formed is then passed through a tower where it isscrubbed with water so that the water-soluble components are absorbed.The fixed gases, comprising carbon monoxide, carbon dioxide, oxygen,nitrogen, and a small amount of unsaturated hydrocarbon which is formed,are vented. The aqueous solution of organic products is then separatedby a suitable series of distillations into the several componentspresent. Th conversion of the isopropyl alcohol into useful products isfound to be 43.5% per pass and the efficiency of conversion, that is,the proportion of feed consumed going to acetone, is

4 about The activity of the catalyst remains substantially constant overmore than 200 hours of continuous operation.

Example III The catalyst may be readily regenerated when the conversionand efficiency drop below an economic level. Regeneration is effected asfollows:

The temperature of the fluidized catalyst bed is lowered to 550 F. andthe flow of air to the system is cut on. The alcohol flow is then slowlyreduced, the reduction in vapor volume in the system being replaced ormade up by gradually increasing the flow of steam so that finally all ofthe vaporized alcohol feed is cut off and only steam is passing throughthe hot catalyst bed. The air flow is then gradually resumed as thesteam flow is slowly cut out. The temperature of the catalyst bed iscarefully controlled by adjusting the air flow so that the bedtemperature does not rise materially above about 550 F. After the unitis on stream with only air flowing through the reactor the catalyst bedtemperature is raised to 650 F. and these conditions are maintaineduntil the carbon deposits on the catalyst particles are burned off whichis indicated when the vent gases contain only a negligible proportion ofcarbon oxides.

To resume the catalytic dehydrogenation reaction after regeneration'ofthe catalyst, the steam flow is resumed as the air is gradually cutofl'.

of entering alcohol and steam vapors is in the desired proportion. Theair flow is then cut in which places the unit fully on stream for thecatalytic dehydrogenation.

It is to be understood that the foregoing detailed description is givenmerely by way of illustration and that many variations may be madetherein without departing from the spirit of my invention.

Having described my invention, what I desire to secure by Letters Patentis:

Process for the production of an improved dehydrogenation catalyst foruse in fluidized form, which comprises forming an aqueous solution ofabout 20 parts by weight of barium hydroxide in about parts by weight ofwater, acidifying the solution with glacial acetic acid, adding about 65parts by weight of cupric nitrate and dissolving the same, adding about3 parts by weight of a 50% by weight aqueous solution of chromicnitrate, introducing about 500 partsby weight of finelydivided inactivealumina having a particle size of about 80 to 325 mesh into thesolution, evaporating the resulting mixture to dryness and then heatingthe coated particles in contact with air at a temperature of 600 to 700F. for a time sufficient to convert the chromium, copper and bariumsalts to their corresponding oxides.

ALEXANDER F. MACLE'AN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

